The present invention relates to a container or chamber capable of containing pressure and fragments produced by an explosion such as a detonation or a deflagration.
Containers of this type are commonly known as detonation chambers. They are used to protect the surroundings by containment of critical manufacturing stages in the production of explosive substances, as test bunkers in test detonations of such substances and for testing of fragmentation weapons as well as for storage of explosive goods in general.
The detonation chamber designs available hitherto have virtually always consisted of solid concrete bunkers dug down into the ground. Certain primarily spherical, thick-walled steel structures are also previously known. The lack of lighter detonation chamber constructions is attributable to some extent to the difficulties in producing reliable strength calculation models. During the last few years, however, modern computer technology has enabled calculation programs to be compiled which make it possible to calculate the strength of multi-walled spherical and cylindrical bodies with a very high degree of accuracy. These calculation programs have opened up the possibilities for manufacturing light-weight detonation chamber designs the strength of which is known.
Some of such light detonation chamber designs are described in our Swedish patent application Nos. 80.06726-7, 81 05585-7 and 83 05758-8. The first of these describes a multi-shell construction with an outer and an inner shell of steel and an intermediate shell of a plastic material which prevents the two steel shells from vibrating in phase. This design has proved to completely fulfil everything it promises in terms of strength but it is difficult to manufacture and even more difficult to repair and therefore relatively expensive. Its low weight, however, makes it suitable for mobile use, e.g. for disarming the increasingly common terrorist bombs and for containing critical process stages in otherwise harmless chemical process plants. In this latter application, it is in fact often a matter of locating the detonation chamber at a height above the ground level that is dictated by the other conditions valid for the process plant.
The second of the aforesaid detonation chamber types is a cylindrical single shell construction with end pieces which have been strengthened in a special way. The third design is a partly double-shelled, preferably cyindrical detonation chamber, the inner complete shell of which is clamped at its end pieces between powerful support beams which are anchored inside the end pieces of its cylindrical outer shell. This design is relatively easy to manufacture and is also relatively easy to repair. The cylindrical inner mantle of the chamber is in fact that part which will be damaged in the first instance and this part can be replaced after the outer shell of the chamber has been divided straight across and pulled apart. The repair is then concluded by welding the outer shell together. Although such a replacement of the inner shell is relatively simple in theory it will nevertheless be a rather expensive and time consuming procedure, partly in view of all the qualified welding work involved.
The risk of damage to detonation chambers intended for test purposes originates primarily from firing of charges giving rise to fragments.